Is cracking your back or knuckles bad for you and what happens when a joint cracks? 

Q26:

From knuckles to knees, backs to necks, most of us can recognize the sound of a joint ‘cracking’. Habitual joint poppers have likely heard negative rumours linking their habit to arthritis or other joint dysfunction- but are these rumours true?

First off, what happens when a joint cracks? 

Most joints in our body contain what is called synovial fluid. This fluid helps lubricate the joint surfaces much like WD-40 does for door hinges. When a joint is placed in a position where it audibly ‘cracks’ , the joint capsule gets stretched and the volume between the bones increases. For a split second, there is a negative pressure created as the fluid seeps to the newly acquired space- this creates the sound of a pop, click or crack. So, its fluid movement that makes the noise, not the contact of bone.

Does joint cracking lead to arthritis?

There is no concrete evidence that links repetitive joint cracking to arthritis. Researchers have in fact done crazy things such as crack their right knuckles repetitively for periods of time and then used X-rays to compare their two hands over time- no arthritic changes found. 

If cracking feels good and doesn’t cause arthritis, than should I do it every day?

The answer is no. Just because arthritic changes aren’t being stimulated, it doesn’t mean that other joint dysfunction isn’t being caused.   Remember what I mentioned above, the actual sound of the crack is caused by a negative pressure created by the joint- so if that pressure change is created in a loose joint, it cracks too (contrary to popular belief). For those loose (or hyper mobile) joints, daily cracking can certainly lead to problems. 

In summary, the reason why Physio’s use joint manipulation (‘cracking’) is to restore the quality and quantity of movement- and its very effective:) Once the movement is restored, they use exercises to facilitate movement through the newly achieved range or movement pattern. After this is achieved, the need for cracking is no longer necessary. 

Fraser